Habitat

Lake whitefish are found mainly in large, cold, freshwater lakes and their drainage basins. They may occasionally enter brackish water. They make small, seasonal migrations between different water depths. They are found in deeper water in summer and winter, returning to shallower water in spring and then again in fall or early winter to spawn over rocky shoals and reefs along lakeshores. They can be found at water depths from 5 to 128 meters or deeper, although ranges of 15 to 37 meters are more typical. (Becker, 1983; Luna, 2008; Michigan Department of Natural Resources, 2008)

Physical Description

Lake whitefish average 457 mm in length, although there is large variation in size in local populations. They are covered in scales that range from pea green or almost brown dorsally to silvery white ventrally. The sides have a bluish hue and the fins are nearly transparent. There are two dorsal fins, including an adipose fin which is sometimes larger in males. Dorsal and anal fin rays are usually 11 (range 10-12), pectoral fin rays are from 14 to 17. The nose is blunt, with a small, subterminal mouth. Lake whitefish are long and laterally compressed, as are most salmonids. Males and females have breeding tubercles on the head and body. The maximum recorded weight was 19 kg (Lake Superior, 1918), although lake whitefish are considered very large at 9 kg. Average weight is more like 1.8 kg. The maximum recorded length was 100 cm, all individuals longer than 467 mm are considered mature adults. (Becker, 1983; Luna, 2008; Michigan Department of Natural Resources, 2008)

Development

Lake whitefish spawn over shallow water shoals. Spawning occurs in fall and early winter and the eggs are broadcast over the shoals, where they settle to the bottom. Eggs hatch in March or early April, taking about 133 days to hatch in waters averaging 1.7 degrees Celsius. Time to hatching increases with decreasing water temperature. In laboratory settings, optimum water temperature for incubation is 3.2 to 8.1 degrees Celsius. Hatching took only 41.7 days in water at 10 degrees Celsius, and 182 days at 0.5 degrees Celsius. Larvae average 13.25 mm in length at hatching and grow about 25 mm per month in their first season. There is little known about lake whitefish development between the larval and adult stages. (Becker, 1983)

Reproduction

Lake whitefish spawn in large groups over shallow water shoals in fall and early winter. Spawning occurs at night. Females repeatedly rise to the water's surface while releasing eggs. They are accompanied by either one or two males who simultaneously release their milt onto the eggs. Spawning is accompanied by a lot of jumping and surface activity. (Becker, 1983)

Lake whitefish spawn in the fall or early winter and eggs hatch in the early spring. Females release thousands of eggs when they spawn, the number of eggs depends on body size. One female that weighed 907 g had 25,000 eggs and another female that weighed 5.9 kg had 130,000 eggs. Males mature at a minimum length of 368 mm, females at 419 mm. (Becker, 1983)

Lake whitefish males and females do not care for their young after the eggs have been fertilized.

Parental Investment

no parental involvement

pre-fertilization

provisioning

protecting

female

Lifespan/Longevity

Most mortality of lake whitefish occurs at the egg and larval stages. Only about 13% of eggs survive to become larvae and larvae are heavily preyed on by larger fish. The maximum recorded age of a lake whitefish was 50 years old, although maximum ages of 25 years are more typical. (Becker, 1983; Luna, 2008)

Range lifespanStatus: wild

50 (high) years

Typical lifespanStatus: wild

25 (high) years

Behavior

Lake whitefish are fairly sedentary in the Great Lakes, although they make seasonal movements between deep and shallow water. They typically make 4 short, seasonal migrations: from deep to shallow water in the spring, back to deep water in summer as water temperatures rise, to spawning areas in shallow water in the fall and early winter, and back to deep water in the winter. Lake whitefish are social and are always found in schools. (Luna, 2008; Michigan Department of Natural Resources, 2008)

Home Range

Total distances traveled during migrations have been recorded at 8 to 242 km, but the vast majority of fish do not travel more than 40 km. Schools of lake whitefish seem to remain fairly local in their movements. (Becker, 1983)

Communication and Perception

Like most fish, lake whitefish have a lateral line system that allows them to detect water movement. They also have good vision and sense of smell. In mating, tactile cues may be important as males and females coordinate to release eggs and sperm.

Economic Importance for Humans: Positive

Lake whitefish have long formed the basis for important subsistence and commercial fisheries. They are not commonly sought as gamefish, although more anglers are beginning to seek them out. They are difficult to catch with hooks because of the deep water they sometimes inhabit and small mouths. Lake whitefish flesh is considered delicate and delicious and the roe is valued for caviar. (Luna, 2008; Michigan Department of Natural Resources, 2008)

Economic Importance for Humans: Negative

There are no adverse effects of lake whitefish on humans.

Conservation Status

Overfishing and environmental degradation caused a near collapse of lake whitefish fisheries in the Great Lakes during the early part of the 20th century. Water quality improvement and fishery management has improved populations since then, although local populations remain threatened and the health of lake whitefish stocks has not fully recovered under continuing commercial fishing pressure. (Becker, 1983; Michigan Department of Natural Resources, 2008)

Other Comments

Contributors

Tanya Dewey (author), Animal Diversity Web.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal

active during the day, 2. lasting for one day.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

freshwater

mainly lives in water that is not salty.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

Becker, G. 1983. Fishes of Wisconsin. Madison, Wisconsin: The University of Wisconsin Press.

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The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
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Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.